Control for helper locomotive



NW. 16, 1965 J. p. I-IuGI-IsoN ETAL 3,217,662

CONTROL 5 01i HELPER LOCOMOTIVE Filed March 3, 1961 3 Sheets-Sheet l 9 5,7 8 AFT HELPER 6 FORE FORE MAIN CARS LOCOMOTIVE CARS CARS W LOCOMOTIVE1 25 @0 ()(D DIRECTION I DETECTOR I I I I I l I I I I I I I TACH. GEN. iJ TG f I g I I 2l3 f VOLTAGE g VS.SPEED SHAPING UNIT INVENTORS. J. D.HUGHSON AND R.B.HANER JR.

THEIR ATTORNEY 1965 J. D. HUGHSON ETAL 7,

CONTROL FOR HELPER LOCOMOTIVE 3 Sheets-Sheet 2 Filed March 3, 1961 a N D\0 W 2 mm Y m R w NJ N m R N T IGN T UA .A HH R DB. B JR H T B 4 2 4 M 82 2 mm r w -l r 3 2 O 2 w 5 abs 1965 J. D. HUGHSON ETAL 3,217,662

CONTROL FOR HELPER LOCOMOTIVE Filed March 3, 1961 3 Sheets-Sheet 5 FASTI87 I34 I59 207 307 MED. FAST I32, EH55 )"Y I I84 F 306 I l I80LOCOMOTIVE 205 305 I I CONTROL 304$ l I I MED. SLO\W PPA T F l I I A RAus i 3 I I I SLOW I78 62 I' I I IDLE 7? I 'I,7\/ I l l BRK. I76 I I Il75 I I I I I I I I l I I I l I I I I I I I I-h-Ij- I- I I I R- l |I7O Il I I LI I I I l I MEDIUM sPEEDI I I 203 I LOW SPEED I M I 20 I72 4R AIRBRAKE 65 AIR BRAKE JD Hu'I-Tgfi fifin EMERGENCY PRESSURE R'B' HANER JRDETECTOR VALVE VALVE /7% THEIR ATTORNEY United States Patent 3,217,662CONTROL FOR HELPER LOCOMGTIVE J. Donald Hughson, Rochester, and RobertB. Haner, 3L, Scottsville, N.Y., assignors to General Signal CorporationFiled Mar. 3, 1961, Ser. No. 93,116 Claims. (Cl. 1051) The presentinvention relates to a method and system for operating a train ofrailroad cars by more than one locomotive, and more particularly to amethod and system for controlling the operation of a helper locomotivethat is used for assisting the main or lead locomotive in pulling atrain of railroad cars.

Specifically, the present invention relates to a method and system forcontrolling a helper locomotive in accordance with the amount of pullingor pushing force to which a helper locomotive is subjected whenconnected in a train of cars.

It is common practice to provide a helper locomotive unit which isconnected directly behind the main locomotive unit and has controlsinterconnected therewith to provide the necessary tractive effort andpower for operating a long train. Although this multiple directlyconnected locomotive unit has enough power theoretically to pullsubstantially twice as many railroad cars over a certain terrain as asingle locomotive unit, the number of cars that are able to be includedin such a train is limited, from a practical standpoint, by the strengthof the drawbars and couplings, and the individual cars. A train having anumber of cars in excess of this practical limit results in damageddrawbars, couplings, and not infrequently damage to the frames of theindividual cars.

Heretofore in an attempt to overcome this practical limit of the lengthof a train pulled by more than one locomotive, and to more evenlydistribute the force exerted on the couplings of the individual cars, ithas been proposed to position the helper locomotive in the trainremotely from the main locomotive. The operation of the helperlocomotive is then controlled from the main locomotive by acommunication link, such as by radio communication, to in effectconstitute a multiple locomotive unit. However, such a system has manydisadvantages. For example, it is necessary to install and maintainremote control apparatus on both the main and helper locomotives. Also,in radio frequency systems, the communication link is unreliable in thatit may be disrupted by extraneous electrical influences. Because of theimpracticability of obtaining an isolated radio frequency for such asystem, the prior proposed system was rendered even less reliable byusing the same frequency as that used for voice communication.

One object of this invention is to provide an improved method and systemfor controlling the operation of a helper locomotive that is used toassist the main locomotive in pulling a train of railroad cars.

Another object of this invention is to provide an improved method andsystem for operating a helper locomotive which insures that the helperlocomotive is carrying its proportionate share of the train load.

Another object of the invention is to provide a method and system forcontrolling the operation of a helper locomotive wherein the amount offorce in tension or compression to which the helper locomotive issubjected determines the proper control of the helper locomotive.

Another object of this invention is to provide a locomotive controlsystem wherein the actual speed of the controlled locomotive modifiesthe control provided by the forces in tension or compression to whichthe controlled locomotive is subjected.

Another object of this invention is to provide a helper locomotivecontrol system that utilizes the force at the coupling to control thelocomotive, and which system has means for locking out the controlequipment of the helper locomotive in the event of malfunction.

A further object of this invention is to provide a system for operatinga helper locomotive wherein the helper locomotive is properly controlledupon the application of the emergency brakes of the main locomotive.

A further object of this invention is to provide a system of thecharacter described for controlling the operation of a helper locomotivewhich is effective to provide the proper control for the locomotive inboth directions of travel.

A further object of this invention is to provide a system forcontrolling the operation of a helper locomotive in accordance with theamount of tensile or compressive force that is present at one of thedrawbars of the helper locomotive when the locomotive is placedintermediate the ends of a train remote from the main locomotive.

Other objects of this invention will become apparent from the drawings,the specification, and the appended claims.

In the drawings:

FIGS. 1A, 1B and 1C, when placed side by side illustrate schematicallythe apparatus and circuitry of a helper locomotive control systemconstructed according to one embodiment of the invention.

FIG. 2 schematically illustrates, by way of example, one of the triggercircuits used in this embodiment of the invention for controlling, inefiect, the throttle of the helper locomotive; and

FIG. 3 schematically illustrates, by way of example, one of the triggercircuits used in this embodiment of the invention for controlling thebraking of the helper locomotive.

According to the present invention, the helper locomotive is coupled tothe train remotely from the main locomotive in accordance withindividual requirements of practice. The force in tension or compressionto which the helper locomotive is subjected when the main locomotiveapplies tractive effort is sensed and converted into an electricalsignal, the value and character of which corresponds to the amount ofand direction of this force. The character and value of this electricalsignal is then caused to selectively operate the throttle or brakecontrol apparatus of the helper locomotive to cause the helperlocomotive to move with a predetermined power and speed to reduce thisforce to a predetermined value. The actual speed of the helperlocomotive provides another electrical signal which modifies thethrottle control as provided by the electrical signal which is caused bythe heretofore mentioned force. With this method, the helper locomotiveis controlled to travel at the proper speed and provide the propertractive effort so that it assumes its proportionate share of the trainload.

In the illustrated embodiment of the invention, the helper locomotive isplaced intermediate the ends of a train with cars coupled to the frontdrawbar or coupling of the helper locomotive and cars coupled to therear coupling or drawbar of the helper locomotive. The actual positionof the helper locomotive relative to the number of cars locate-d eitherahead of, or behind the locomotive, in this embodiment of the invention,depends on the proportionate share of the power that the helperlocomotive is to provide. Thus, in a train of cars, for example, if thehelper locomotive has sixty cars in front and forty cars coupled to therear, it is required to provide approximately 40% of the total power foroperating the train.

When the helper locomotive is pulling its proportionate share of thetrain load, there is little or no force applied to the front coupling ordrawbar of the locomotive. When the helper locomotive is operating in aforward direction and pulling a disproportionate share of the train loadwhich is less than that required, there is a force in tension on thefront draw b-ar of the helper locomotive; and when this disproportionateshare is greater than that required, there is a force in compression onthe front drawbar.

In the illustrated embodiment of the invention, the locomotive motor iscontrolled by the force that is on the forward coupling of the helperlocomotive in such a way that the locomotive is constantly operating tobring this force to substantially zero. If there is a force in tensionat the front drawbar, the system operates to increase the tractiveeffort of the locomotive to decrease this force. If this force is incompression the system operates to decrease the tractive effort toreduce the force. Also, the system is so arranged to modify the effectof this force in controlling the motor control apparatus depending uponthe speed that the helper locomotive is actually traveling. Moreover,the system further modifies the effect of this coupling force when thehelper locomotive is traveling at a low rate of speed, such as wouldoccur when it first starts moving to prevent wheel slippage and providesmooth operation; and also provide for proper operation of the helperlocomotive to share the proportionate share of the load when travelingin a reverse direction.

Referring to the drawings, and particularly to FIG. 1A, a train of carsis diagrammatically illustrated fragmentarily, which includes a helperlocomotive 5 that is connected by its front drawbar or coupling 6 to aplurality of cars 7. Connected to the front of the car 7 is a main orlead locomotive 8. A plurality of cars 9 are connected to the rear ofthe helper locomotive 5. The helper locomotive 5 may be any conventionallocomotive, which is equipped with a prime mover control system which ineffect advances the throttle in response to the selective energizationof the motor control apparatus. In the illustrated embodiment, the primemover control system is selectively operated by applying energy to oneof a plurality of wires to slow down, speed up, or brake the helperlocomotive.

A force responsive device, or so-called strain gauge 10 is connected tothe coupling 6 so as to be responsive to the forces either in tension orcompression that are present at this coupling 6. The strain gauge 10 maybe of any well known type which operates to supply a distinctive outputsignal, the value of which corresponds to the degree of force at thecoupling 6, and is distinctive to the direction of force at the coupling6, that is, whether the force is in tension or compression. In thepresent embodiment, the gauge 10 comprises a strainable element 12 whichis connected in a bridge circuit 11 with resistors 13, 14 and 15. Asource of potential, such as a battery 16 supplies energy to oppositediagonals of this bridge circuit 11. When the element 12 iscomparatively free of any force either in tension or compression, thebridge circuit 11 is balanced thereby producing no output potentialacross wires 17 and 18 which are connected to the opposite diagonals ofthe bridge circuit 11. A force in tension exerted on the element 12unbalances the bridge circuit 11 to produce an output voltage of onepolarity across the output wires 17 and 18, the value of whichcorresponds to the degree of tensile force. A force in compression onthe element 12 unbalances the bridge circuit 11 in an opposite manner toproduce an output voltage of opposite polarity across the wires 17 and'18. In describing the present embodiment of the invention, it isassumed that a force in tension will produce an output voltage ofpositive polarity across the wires 17 and 18, that is, wire 17 ispositive relative to wire 18. A force in compression will cause anegative output voltage across the wires 1'7 and 18, that is, the wire17 is negative relative to the wire 18.

The output wires 17 and 18 of the gauge 10 are connected through polechanging connections to the input of an amplifier 24 These pole changingconnections are contacts 22 and 24 of a relay RD, Which contacts arewhich either in an energized position or a deenergized positiondepending upon the forward or reverse direction of the train. The relayRD is connected to a direction detector or so called zero motion switch25, which is connected to the helper locomotives in such a way that itoperates to cause the lower winding of the relay RD to be energized,thereby closing the back contacts 22 and 24 when the locomotive is atstop or traveling in a forward direction; and causes the upper windingof the relay RD to be energized, thereby closing the front contacts 22and 24 when the helper locomotive is traveling in a reverse direction.

The output of the amplifier 20 is connected to the input of anintegrator 31 This integrator is comprised of a resistor 32, a capacitor34, and an amplifier 35, which are connected in a well known circuitarrangement, to integrate the value of the output potential from theamplifier 20, regardless of its polarity.

The integrated output potential of the integrator 39 is applied overwire 45 to the detection triggers by the closing of a contact 36. Theintegrated potential in the integrator 30 is periodically cleared by theclosing of a contact 38, which completes a circuit for discharging thecapacitor 34 and dispelling the voltage.

The opening and closing of the contacts 36 and 38 are controlled by aconventional timing mechanism 43 through cams 41 and 42. These cams 41and 42, which are rotated at a predetermined rate of speed in aclockwise direction as viewed in FIG. 1A, are so arranged to cause thecontact 38 to be opened for a predetermined period of time, such as tenseconds, for example, and then is closed momentarily to reset theintegrator to zero. The cams 41 and 42 are further so arranged that thecontact 36 is closed momentarily just prior to the closing of thecontact 38. Thus, during operation, while contact 38 is open, cam 41first closes and then opens contact 36, and cam 42 then closes contact38 to dispel the potential in the integrator 30. Thus, the integrator 30and the timer so cooperate with the strain gauge 10 that a pulse ofintegrated potential is provided to the trigger circuits periodically.The value of this pulse is that which has been integrated during the tensecond period since the last output pulse from the integrator 3t) whencontact 33 was open.

During the momentary closing of the contact 36, the output voltage fromthe integrator 30 is applied over wire 45 to a voltage dividing resistor50. The resistor St) is provided with spaced taps 51, 52, 53, 54, and55. Each tap of the resistor is connected through a respective resistor56, 57, 58, 59, and to the input of respective throttle trigger circuits1TC, 2TC, 3TC, 4TC, and STC.

The trigger circuits 1TC through 5TC are so constructed and connected tothe resistor 50 through its respective taps, that a relatively weakintegrated pulse of predetermined value and positive potential causestrigger circuit 1TC only to fire. A slightly stronger pulse ofpredetermined potential and positive value causes trigger circuits 1TCand ZTC to fire. Similarly, a still stronger positive pulse ofintegrated voltage causes the additional firing of trigger circuit ETC,and so on until the maximum integrated positive pulse of predeterminedvalue applied to the resistor 50 results in the firing of all thetrigger circuits 1TC through STC. Each of the trigger circuits 1TCthrough STC when fired, operate a respective relay 1T through 5T. Theserelays are held picked up only long enough to permit the hereinaftermentioned stepping switches to move from one limit position to another,if required, whenever its respective associated trigger circuit isfired. Connected to the trigger circuit 1T C is a repeater relay 1TPwhich is energized when the relay 1T is picked up.

The trigger circuits 1TC through STC for operating their respectiverelays 1T through 5T are identical circuit configurations, and a typicalcircuit arrangement for the operation of relay 1T by the trigger circuit1TC is illustrated schematically in FIG. 2 by way of example. Thetypical trigger circuit 1TC for operating the relay IT is comprised ofPNP transistors 62 and 63. These transistors are connected by a commonemitter connection through a resistor 64 to a source of positive biasingpotential. The collector terminal of transistor 62 is connected througha resistor 65 to the base of the transistor 63. The collector of thetransistor 62 is also connected through a resistor 67 and the winding ofa relay 1T to the collector of the transistor 63. The base of thetransistor 62 is connected to a wire 68 which constitutes the input ofthe trigger circuit from the tap 51 of the resistor 50. The positiveemitter bias maintains the transistor 62 in a normally conductive statewhich causes the transistor 63 to be normally nonconductive or cut off.When a positive voltage pulse is applied to the base of the transistor62 over the wire 68, the transistor 62 is cut off during the pulse,which causes the transistor 63 to conduct at this time. The momentaryconducting of transistor 63 energizes the relay 1T.

In the trigger circuit 1TC only of the trigger circuits 1TC through STC,there is a contact 70 which moves from back to front and then back. Eachtime the contact 70 is closed at its front during this movement, acapacitor 72 is charged through a circuit which extends from (-1-) andincludes the front contact 70, and the capacitor 72 to The capacitor 72is discharged each time the contact 70 is closed at its back through awire 74 and the winding of the relay 1TP (FIG. 1B), and a capacitor '76to The capacitor 76 serves to maintain the relay constantly picked upduring the time interval between the pulses from the integrator 30.

Also connected to the taps 51, 52 and 53 respectively of the resistor 50through isolating resistors 80, 81, and 82 are brake trigger circuits1BTC, 2BTC, and 3BTC respectively. The trigger circuits IBTC, ZBTC and3BTC are so constituted and connected to the divider 50 that arelatively weak integrated potential of negative value causes thetrigger circuit 1BTC only to fire. A stronger negative pulse will causeboth the trigger circuits lBTC and ZBTC to fire and the maximumintegrated negative pulse from the resistor 50 causes all three triggercircuits 1BTC, ZBTC and 3BTC to fire. Connected to the output of each ofthese trigger circuits is a repeater relay 1BTP, ZBTP and 3BTP,respectively.

The trigger circuit 1BTC through 3BTC are identical circuitconfigurations, and a typical circuit arrangement for the triggercircuit 1BTC is illustrated schematically in FIG. 3 by way of example.This trigger circuit is comprised of NPN transistors 92 and 93. Theemitters of the transistors 92 and 93 are connected through a resistor94 to a common source of negative biasing potential. The collector oftransistor 92 is connected through a resistor 95 to the base of thetransistor 93. The collector of the transistor 92 is also connectedthrough a resistor 97 and the winding of a relay 1BT to the collector ofthe transistor 93. The base of the transistor 92 is connected by a wire98 to the tap 51 of the resistor 50 through the resistor 86 toconstitute the input of the trigger circuit. The negative emitter biasmaintains the transistor 92 in a normally conductive state which causesthe transistor 93 to be normally nonconductive. When a negative voltagepulse is applied to the base of the transistor 92 over the wire 98, thetransistor 92 becomes nonconductive which causes the transistor 93 toconduct during the pulse period. The conducting of the transistor 93 inresponse to the negative voltage pulse energizes the relay 1BT whichcauses a movement of contact 1% of the relay 1BT from back to front toback. Similar to the operation of the contact 71) in the trigger circuit1TC, the operation of the contact 100 causes a capacitor 102 to chargeand then discharge through the front and back contacts 1%, respectii ly.Also, the discharging of the capacitor 1132 causes the relay 1BTP to beenergized over a wire 1114 at the output of the trigger circuit. Acapacitor 106 also maintains the relay energized during the timeinterval of ten seconds since the previous pulse from the integrator 30picked up the 1BT relay. The repeater relays 213T and 3BT operate in thesame manner.

A slow drop away relay ZS is provided to be deenergized upon the pickingup of relay 1TP or 1BTP. This relay will stay picked up after beingdeenergized longer than the relays 1T through 5T, but shorter than thetime interval between output pulse from the integrator 30.

The trigger relays 1T through 5T, 1BT and ZBTP, and the relay ZS areeach provided with a respective contact 110 through 117 which are soconnected in a circuit organization to control the operation of astepping switch as will be described hereinafter. The ZS relay isnormally energized from energy through a contact 118 of relay 1T1contact 119 of relay lBTP to negative energy. Thus, the ZS relay isenergized Whenever the conditions are such that neither 1TC or 1BTC aretriggered at the end of a time period, for example when the couplerstress is in the range close to zero.

The stepping switch is comprised of three mounting discs or so calledwafers W1, W2, and W3. Positioned on each of these waters are aplurality of angularly spaced contact terminals C1, C2, C3, C4, C5, C6,and C7. On the wafer W1, the contact terminals are referred to at 1C1,1C2, etc. through 1C7. On the wafer W2, the contact terminals arereferred to at 2C1, 2C2, etc. through 2C7; and on the wafer W3, thecontact terminals are referred to at 3C1, 3C2, etc. through 3C7.Rotatably mounted on each wafer is a contact arm which is adapted toengage each one of the associated terminals C1 through C7. A contact arm121 is mounted on wafer W1, a contact arm 122 is mounted on wafer W2;and a contact arm 123 is mounted on wafer W3.

The contact arms 121, 122 and 123 are so connected mechanically tooperate in synchronism step-by-step either upwardly to engage the nextadjacent higher numbered contact terminal or downwardly to engage thenext adjacent lower numbered contact terminal. The contact arms 121,122, and 123 may be connected by any well known ratchet type mechanismwhich will advance the arms simultaneously to the next adjacentterminal. A relay 125 (FIG. 1C) operates the ratchet mechanism toaccomplish the aforesaid results. The relay 125 is provided with a downstep winding D, which when energized causes the mechanism to move thearms 121, 122, and 123 downwardly as viewed in FIGS. 1B and 1C to engagethe next lower adjacent contact terminal, and an up step winding U,which when energized causes the mechanism to move the arms 121, 122 and123 upwardly to engage the next higher adjacent contact terminal.

The contact terminals 1C on the wafer W1 and the contact terminals 2C onthe wafer W2 are connected electrically to selectively complete adistinct circuit through either the arm 121 or 122 to the winding U orD, respectively, of the relay 125 depending upon the condition of therelays 1T through 5T, 113T and ZBT, and the relay ZS in accordance withthe positions of the arms 121 and 122. The contact terminal 1C1 isconnected by a wire 131 and diodes as shown to the contact terminal 2C3.The terminal 1C3 is connected by a wire 132 and diodes as shown to theterminal 2C5. The terminal 1C4 is connected by a wire 133 and diodes asshown to the terminal 2C6. The terminal 1C5 is connected by a wire 134and diodes as shown to the terminal 2C7. The terminal 1C6 is connectedby a wire 135 to the front contact 116 of the relay ST. The terminal 1C7on the wafer W1 has no circuit connection and merely constitutes thelimit of upward movement of the arm 121. The terminal 2C1 on the waferW2 has no circuit connection and merely constitutes the limit ofdownward movement of the arm 122.

Relays BR, ZS and ZBTP through their respective front contacts 121), 117and 113 apply positive energy to the 130 line. Positive energy isapplied to the 132 line through the BR and ZS relay contacts 120 and 117respectively and 2T relay front contact 111 and 3T relay back contact114. Positive energy is applied to the wire 133 through the back contact115 of the relay 4T when the relays BR, ZS, 2T and 3T are energized.Energy is applied to the Wire 13 1 through the back contact 116 of therelay T when the relays 2T, 3T, 4T, BR and ZS are picked up. When all ofthe relays BR, ZS and 2T through 5T are picked up, energy is applied tothe wire 135.

A plurality of unidirectional current conducting devices or diodes 141through 145, respectively, are connected across adjacent contactterminals 1C1 through 1C6 to the wires 136 through 135. These diodes 141through'145 permit positive energy applied to one of the wires 13%through 135 to be applied to the lower numbered contact terminalsadjacent the terminal connected to this wire. For example, when positiveenergy is applied to the wire 135, the diodes 141 through 145 conductthis energy to all of the contacts 1C5 down to 1C1. When positive energyis applied to the wire 133, for example, positive energy is conductednot only to the terminal 1C4 but also through the diode 143 to theterminal 1C3, and the diode 142 to the terminal 1C2, and the diode 141to the terminal 1C1. A plurality of diodes 14-6 through 149 are eachconnected in a respective wire 131 132, 133 and 134 to prevent thispositive energy from being conducted to the other wires 131), 132, 133,and 134.

Similarly, a plurality of unidirectional current conducting devices ordiodes 151 through 155 are each connected across adjacent ones of thecontact terminals 2C2 through 2C7 to the wires 131) through 134. Thesediodes are arranged to conduct current opposite to that of diodes 141through 145 so that when positive energy is applied to the wire 133 forexample, this energy will be conducted to the higher numbered terminals,such as 2C7 and terminal 2C6 of the wafer W2 but blocks any conductionof current to the lower numbered contact terminals mounted on the waferW2. Diodes 156 through 1519 are each connected in one of the wires 130,132, 133 and through 134 to prevent the flow of energy from adjacentwire to the other, similar to the diodes 146 through 149.

Thus, when energy is applied to the wire 130, it will be conducted tothe contact terminals 2C3 through 2C7 of the wafer W2 through the diodes152 through 155, and will be blocked from the terminal 2C2 by the diode151. This energy will also be applied to the contact terminal 1C1 of thewafer W1 but will be blocked from any of the other terminals of thewafer W1 because of the diode 141. Assuming that the arms 121 and 122 ofthe Wafer W1 and W2 are in their extreme downward position, and positiveenergy is applied to the wire 132, this positive energy will beconducted through diodes 147, 14-2, 141 and terminal 1C1 of the waferW1, arm

121, wire 161, back contact 162 of the winding U of the relay 125 andthe winding U, to

Back contact 162 and 163 of the stepping relay 125 are arranged so thatthey are closed until the stepping stroke is almost completed. Afteropening they remain open until the ratchet mechanism has returned to itslatching position. This operation is repeated as long as there is energyat the heel of contact 162 or 163. When the relay ZS is dropped awayenergy is applied to either the D or U coil of the relay 125 over wires110 or 169. Since this energizing circuit does not include either backcontact 162 or 163, the relay will stay energized until the potential isremoved from the wires 11% or 1&9, permitting only one step for eachenergization.

Since there is no external connection to terminal 2C1, this pulse ofpositive potential does not affect the wafer W2. Because the energizingcircuit for the winding U of the relay 125 is through its back contact162 the relay operates the ratchet mechanism to advance the contact arms121 and 122 one step from 1C1 and 201 to 1C2 and 2C2, and is thendeenergized to return to its latching position and close contact 162.Positive energy is now applied to the U coil through diodes 147 and 14-2and closed contact 162. Another step is taken with contact 162 openingat the completion of the step and reclosing after the ratchet mechanismrelatches. Arms 121 and 122 rest on contacts 1C3 and 2C3 respectively.Positive energy through diode 1 18 causes another step so that arms 121and 122 rest on contacts 104 and 2C4. Now due to the blocking action ofdiodes 143 and 153 no positive energy is applied to either the U coil orD coil of the stepping switch relay so the switch remains in thisposition. Therefore, from the previous description of the steppingswitch and its connecting circuitry it is apparent that the arms 121 and122 of the wafers W1 and W2 are controlled step-by-step or in multiplesteps either upwardly or downwardly depending upon the position of thearms 121 and 122 on the energized or deenergized position of the relaysZS, 1T through 5T, 113T, and ZBTP. As previously mentioned the contactarm 123 of the wafer W3 moves one step upwardly or downwardlysimultaneously with the arms 121 and 122.

The arm 123 and the contacts 3C1 through 3C7 are so connected as todistinctively condition the circuitry for operating the throttle andbrake control system of the locomotive. The energy applied to the arm123 of the wafer W3 is controlled by contacts of relays ER and BR. Therelay ER is operated by an air brake emergency detector valve 165, whichoperates a switch 166. The valve 165 is sensitive to a rapid loss of airpressure in the braking system of the locomotive, such as would occur ifa section of the train should accidentally become uncoupled, othersudden failure of the air brake system, or an emergency brakeapplication were made at the lead locomotive. Under normal conditions,the switch 166 is closed and the relay ER is normally energized by astick circuit which extends from and includes the contact 166, frontcontact 167 of the relay ER and the winding of the relay to If the relayER should drop away because of a sudden loss of pressure, a reset button168 is provided to reestablish the stick circuit after the condition iscorrected. The relay BR is controlled through a contact 170 of an airbrake pressure valve 172. When there is air in the braking system of apredetermined value the contact 1711 is closed and the relay BR isenergized. Thus, when both relays ER and ER are energized positiveenergy is supplied to the arm 123 through front contact 173 of the relayER and front contact 174 of the relay BR. If either one or the other ofthe relays ER and BR is deenergized, this energy is applied to theterminal 3C2 of the wafer W3.

The contacts 3C1 through 3C7 of the wafer W3 are connected in a circuitarrangement to the various throttle and brake control wires of thehelper locomotive for exercising respective distinctive controls for thelocomotive. The terminal 3C1 is connected to a brake control wire 175,which when energized applies the dynamic brakes of the locomotive. Theterminal 3C2 is connected to a wire 176 which when energized causes thelocomotive engine and control circuits to assume the idle condition. Theterminal 3C3 is connected by a wire 177, which when energized controlsthe locomotive at a slow rate of speed. When wire 173 is energized thelocomotive motor is controlled to a medium slow rate of speed throughterminal 3C or 3C5 depending upon the position of contact 180 of a speedrelay 1R. The terminal 3C5 is also connected to apply energy to a wire132 when front contact 1811 of the speed relay 4R is closed to cause thelocomotive motor to operate at a medium rate of speed. When energy isapplied to a wire 124 the locomotive engine is controlled to operate ata medium fast rate of speed through the terminal 3C6 when front contactof a relay 6R is closed. Energy is also supplied to the wire 184 fromthe terminal 3C7 when a back contact 136 of a relay 111R is closed andthe front contact 135 is closed. The locomotive engine is controlled toa fast rate of speed by applying energy to a wire 187. Energy is appliedto this wire from terminal 307 when the front contact 186 is closed. Itshould be noted, that energy may be applied to the wire 176 to cause thelocomotive motor to idle through a circuit which extends from (-1-) andincludes back contact 173 of relay ER and the terminal 3C2, or includesthe front contact 173 of relay ER and the back contact 174 of the relayBR.

Also connected to the helper locomotive is a tachometer generator TGwhich provides output energy to amplifiers 200 and 202, the potentialvalue and frequency of which depends upon the speed that the helperlocomotive 5 is traveling. The output of the amplifier 292 is appliedover a wire 2% to a plurality of high pass filters 204, 205, and 206.Vthen the locomotive is detected by the tachometer generator TG astraveling at four miles per hour, for example, the frequency of thispotential is such as to cause the high pass filter 2114 to energize therelay 4R. When the locomotive is traveling at a speed of six miles perhour, for example, the frequency passed by the high pass filter 235causes the relay 6R to be energized in addition to the relay 4R. Whenthe locomotive is traveling at a speed of ten miles or more per hour,the high pass filter 2% passes a frequency to cause the relay R to beenergized in addition to both the relays 6R and 4R.

The output from the amplifier 200 is applied to the input of a wellknown voltage shaping unit or device 21d which will change the outputfrequency of the amplifier to a voltage proportional to the frequency,in any well known manner. The output voltage is rectified by a bridgerectifier 212, and the DO. output voltage from the rectifier 212 isstored in a capacitor 213. The output from the capacitor 213 isconducted over wires 214 and 215 to opposite ends of a voltage dividingresistor 220. In the illustrated embodiment of the invention, the Wire2214 is assumed to be positive and the wire 215 is negative. The centralpoint of the resistor 220 is connected to ground. The side of theresistor between the wire 214 and ground is provided with a plurality ofspaced taps 221, 222, 223, 224 and 225. The tap 221 is connected throughan isolating resistor 230 to the input 63 of the terminal triggercircuit 1TC. The tap 222 is connected through a resistor 226 to theinput of the trigger circuit 2TC. Also, the taps 223 and 224 of theresistor 220 are connected through respective resistors 227 and 228 tothe input of the trigger circuits 3TC and 4T0 respectively. A tap 225 ofthe resistor 220 is connected through a resistor 229 to the triggercircuit STC.

The negative side of the divider 22% is provided with spaced tapconnections 232, 233 and 234. The tap 232 of the resistor 220 isconnected to the input 98 of the brake trigger circuit lBTC through aresistor 235. The taps 233 and 234 are connected through respectiveresistors 236 and 237 to the trigger circuits ZBTC and 3BTCrespectively.

Thus, the positive D.C. energy from the rectifier 212 is applied throughthe voltage divider 221) to the throttle trigger circuits 1TC throughSTC, and the negative potential is applied to the braking triggercircuits 1BTC through 3BTC. The amplitude of the biasing voltage fromthe divider 22% is governed by the speed of the locomotive; the greaterthe speed, the greater the amplitude of the biasing voltage. Therefore,it is apparent that the voltage output of the tachometer generator TGmodifies, through the voltage dividing network 226, the effect of thepulse output of the integrator 30 in a manner so that both the brakingtrigger circuit inputs and the throttle trigger circuit inputs aremodified by the speed of the locomotive. Moreover, because this biasvoltage is of the same polarity that is required to fire the triggercircuits by a pulse from the divider 50, the greater the amplitude ofthe biasing voltage, the less pulse amplitude required to fire thetrigger circuits from the divider 59. For example, if the coupling 6 issubjected to a strain which is sufiicient to produce a pulse amplitudethat will fire the trigger circuits 1T C and ZTC only when thelocomotive is stopped, this same pulse amplitude is sufficient, perhaps,to fire the trigger circuit 3TC also, when the locomotive is travelingat a certain speed. In the event the locomotive is traveling at apredetermined high rate of speed, a predetermined strain on the coupling6 which would only be sufiicient to fire the trigger circuit 1TC whenthe locomotive is stopped, may be sufiicient perhaps to fire all thetrigger circuits at the rate of speed that the locomotive is traveling.

The locomotive motors which are shown digramrnatically have armaturesgenerally referred to at M1 and M2. These armatures are connected inseries across a plurality of series connected resistors 24d, 241, 242,243, and 244 when the locomotive control circuits are set for dynamicbraking. Also, in parallel with these resistors and connected across themotor armatures M1 and M2 when connected for dynamic braking are twodissipation grids 245 and 246. The field winding 247 of the motor M1 and248 of the motor M2 are connected in series across the main generatorarmature 251). The field 252 of the main generator is connected atopposite ends between the resistors 243 and 244-, and 240 and 241respectively. As shown in FIG. 13, when the relays 1BTP, ZBTP, and 3BTPare deenergized, all the resistors 241, 242, and 243 are shunted out byback contacts 253, 254 and 255. When front contact 255 of relay lBTP isclosed only the resistors 241 and 242 are shunted out. Similarly, whenthe relay ZBTP is energized, the closure of front cont-act 254 resultsin the shorting out of only the resistor 241. When all the relays BTPare energized none of the resistors are shunted out. Thus, the operationof the relays 1BTP through 3BTP provides dynamic braking in increasingdegrees depending upon the condition of these relays BTP.

A more detailed description of this embodiment of the invention will begiven in connection with its operation. The helper locomotive is coupledinto the train under manual control by a hostler. The motor controlswitch is then set to automatic. The timer 4-0 is started to rotate.Because there is no air pressure in the braking system at this time, therelay BR is deenergized, and the engine is started to idle by energizingthe idle control wire 176 through a circuit which extends from andincludes front contact 173 of the relay ER, back contact 174 of therelay BR, the terminal 3C2 of the wafer W3 of the stepping switch, andthe idle control wire 176. When the brake line is pumped up, the idlecontrol wire 176 is maintained enrgized by a circuit which extends fromand includes the front contacts 173 and 174 of the relays ER and BR, arm123 and contact terminal 3C2 of the wafer W3, and the idle wire 176.

When the lead or front locomotive starts to move forwardly, a force intension is placed on the coupler 6, which unbalances the bridge circuit10 to render the output wire 17 more positive than the output wire 18.Since the helper locomotive is not moving when the tension is firstapplied and will move forwardly when it gets underway, the lower windingof the relay RD which is energized remains energized so that its backcontacts 22 and 24 are closed. Thus, the input to the amplifier 20 issuch that the integrator 30 provides positive energy. The integrator 30begins integrating the potential from the bridge 11 when contact 38 isopen, and when the cam 41 of the timer 46 causes the contact 36 toclose, the integrated positive pulse is applied to the voltage dividingnetwork 50 over the wire 45.

In starting the train, it may be that this positive integrated pulse isof sufficient amplitude to cause the trigger circuits lTC through 4TC tofire because the tension on the coupler 6 would be substantial at thistime. It should be recalled that, because the pulse is positive, it hasno etfect on the trigger circuits IBTC through 3BTC. Because the helperlocomotive is not yet under motion when this tension is applied instarting, the tachometer generator TG does not provide any outputbiasing potential. All the relays 1T through 4T are energized upon thefiring of the trigger circuits 1TC through 4TC. The relay 1'11 is heldenergized by its shunting capacitor 76 so that it will remain picked upuntil the timer 41 causes the contact 3:; to again close for applyingthe next subsequent pulse of potential it any. Upon the picking up ofthe relays 1T through 4T, energy is applied to the wire 134 of thestepping switch by a circuit which extends from and includes frontcontacts 121?, 117, 111, 114 and 115 of relays BR, ZS, 2T, CT and 41respectively. The energizing of the wire 134 applies potential to theupstep coil U of the relay 125 through the diodes 149, 144, 143, 142,the arm 121 of the wafer W1, wire 161, back contact 162 of the winding Uand the winding U of the relay 125 to causing arms 121, 122, and 123 tostep up to contacts 1C6, 2C6 and 3C6 in the manner as previouslydescribed.

When the arm 121 engages the terminal 1C6, the arm 123 of the wafer W3is engaging the terminal 3C6 of the wafer W3, but energy is still beingapplied to the medium slow wire 178 of the motor control circuit throughthe back contacts 185 and 180 of the speed indication relays 6R and 4Rrespectively. This prevents the wheels from slipping under conditions ofgreat tension when the locomotive is starting, by not permitting thelocomotive motor to assume a full speed or throttle control condition.

As the speed increases relays 4R, 6R and MR pick up successively toincrease gradually the throttle setting and horsepower developed by thediesel engine.

Before the timer 4 1 permits the next pulse of energy to be applied tothe divider 50, the ZS relay drops away. The relay 1T? remains picked upduring this interval. Assuming that the next pulse of energy is positiveand is of sufiicient force to again fire the trigger circuits 1TCthrough A TC, the stepping switch only moves one step. This is caused bythe deenergized position of the relay ZS which closes a circuit toenergize the coil U of the relay 1235, which circuit extends from andincludes front contact 121 of the relay BR, back contact 117 of therelay ZS, front contact 11d of the relay 1T, wire 109 and the winding Uof the relay to Thus as long as there is a force on the coupling, eachtime the contact 36 of the timer 4%) closes to permit the firing of thetrigger circuit 1TC, the stepping switch will advance only one step,regardless of the degree of force. In the present example, however, onthe second pulse of potential, the stepping switch engaged the contact1C7 which is the limit of its travel, and the throttle is advanced onlybecause the increase of speed of the locomotive causes the relays 4R toNPR to pick up successively.

Assuming that the train has been traveling for some time with little orno force in tension or compression at the coupling a, and the lead ormain locomotive slows down, a force in compression will occur at thecoupling 6. The force in compression unbalances the bridge circuit tocause the wire 17 to be negative thereby producing an integrated pulseover wire when the contact 36 closes which is of negative potential. Thetrigger circuits 1BTC through 3BTC will fire, depending upon theamplitude of this negative pulse as modified by the biasing potentialfrom the divider 220. Assuming that this negative pulse is of sufficientvalue to cause both the trigger circuits 1BTC and ZBTC to fire, thusenergizing the relays llBTP and ZBTP, the stepping switch will stepdownwardly until arm 121 engages the contact 1C2. The circuit forstepping the switch in multiple under these conditions extends from andincludes front contact 120 of the relay BR, front contact 117 of therelay ZS, front contact 113 of the relay ZBTP, the wire 1311, diode 156,the diodes 152 through 155, terminal 2C7 of the wafer W2, arm 122, backcontact 163 of the relay 125 and the winding D of the relay to Arm 123of the wafer W3 also moves downwardly to energize the idle wire 176. Thenext time that the contact 36 of the timer 40 closes and a force incompression still exists, which is great enough to fire 1.2. the triggercircuit 1BTC, the stepping switch will move downwardly one step by acircuit which extends from and includes front contact 121) of the relayBR, back contact 117 of the relay ZS, front contact 112 of the relay1BT, wire and the winding of the relay D to 1f the first force incompression which occurred when the train slowed down was only greatenough to result in the firing of the trigger circuit 1BTC, the steppingswitch would move downwardly only one step at a time each time thecontact 36 closed by a circuit which extends from and includes frontcontact of the relay BR, front contact 117 of the relay ZS, back contact113 of the relay ZBTP, front contact 112 of the relay 113T, wire 116,and the winding W of the relay to It should also be noted, that thepicking up of the relays EBTP through 3BPT also increases the dynamicbraking in the motor.

If the BR relay should become deenergized because of an application ofthe brakes of the main locomotive, the back contact 12% would closewhich also energizes the 13d wire immediately irregardless of theclosing of the contact 36 of the timer by an obvious circuit. Thedropping away of the relay BR (FIG. 10) also simultaneously appliedenergy to the idle wire 176 through back contact 174 of the relay.Similarly a sudden loss of air pressure, which denotes a malfunction ofthe braking system, will cause the relay ER to drop away which energizesthe idle control wire 1'76 by the closing of back contact 173 of therelay.

Thus, from the preceding description of the operation, it is apparentthat the system will cause a stepping of the stepper switch to aposition which will tend to make the force in the coupling 6 which isinsuihcient to cause the firing of either the trigger circuit 1TC orllBTC. Only one corrective step is taken at a time unless a period oflittle or no strain has existed prior to the triggering of the triggercircuits TC or BTC. In the event a period of little or no force hasexisted prior to the triggering, multiple steps can be taken dependingupon the position of the arms of the stepping switch and the amount ofthe force at the coupling.

If the train should reverse its direction of travel, the lead locomotivewould cause a force in compression against the coupler s of the helperlocomotive. This at first would force the locomotives to move rearwardlywhich would cause the relay RD to pick up to close its front contacts 22and 24. This force in compression thus causes a positive signal to beintegrated in the integrator 34) for controlling the triggers 1TCthrough ESTC to operate the helper 5 locomotive in a reverse direction.Also, under these circumstances, a force in tension would provide anegative pulse in the integrator 3d thus applying the brakes of thehelper locomotive. The foregoing examples of the operation of thisembodiment of the invention under a set of typical operating conditionswill render obvious the operation of the system under other given setsof trafiic or operating conditions.

It is understood, that more or less trigger circuits TC or BTC may beused in accordance with the requirements of practice. The triggercircuits TC or BTC are shown herein as being transistor multivibratorcircuits which are preferred because of their resistance to shock.However, any suitable type of trigger circuits may be used in practicingthis invention.

Although, the helper locomotive herein illustrated is positionedintermediate the ends of a train, it is understood that a method andsystem according to the present invention is adaptable to properlycontrol the helper locomotive regardless of its position in the train.This embodiment of the invention controls the locomotive motor toconstantly bring the force at the forward coupling to substantiallyzero. However, it is understood that a system according to the presentinvention could be arranged to respond to a force on any other couplingof the locomotive on the train, and constantly attempt to bring theforce at this coupling to some predetermined force either in tension orcompression.

Thus, I have provided an improved system for operating a locomotive thatis coupled to a train which will at all times control the locomotive atthe proper speed and tractive effort. Further, I have provided a systemwhich compensates for and irons out any time shocks to which the drawbaror coupling of the locomotive will be subjected during operation, and asystem which modifies the control of the locomotive motor in accordancewith the actual speed of the locomotive, and causes the helperlocomotive to respond practically instantaneously to any decrease orincrease in the speed of the main or lead locomotive or in a change ofproportion of the load that the helper locomotive is to pull. It isapparent, that this system not only improves the operation of a helperlocomotive to aid in providing additional tractive effort for pulling atrain, but it also provides additional dynamic braking.

Having thus described one specific embodiment of the present invention,it is to be understood that various adaptations, modifications, andalterations may be made in accordance with the requirements of practice,without in any manner departing from the spirit or scope of the presentinvention.

What I claim is:

1. A system for operating a helper locomotive that is coupled to a trainof cars to which a main locomotive is also coupled, said systemcomprising means for selectively operating the throttle and brakingcontrol of the helper locomotive, strain responsive means mounted todetect the degree of force between the helper locomotive and a coupledcar of the train, electrical means operatively connected to said strainresponsive means to produce an electrical signal proportional to thedetected force, control means responsive to said electrical signal toselectively operate the throttle and braking means to maintain saiddetected force within limits such that the helper locomotive isproviding the power for a predetermined portion of the train.

2. A system according to claim 1 wherein said electrical means isoperative to produce an output signal of one polarity when said strainresponsive means detects a force in compression and an output signal ofopposite polarity when said strain responsive means detects a force intension.

3. A system according to claim 1 wherein said control means includes anintegrating means connected to the output of said electrical meanseffective to integrate said electrical signal, and timing meansoperatively connected to said integrating means to periodically producean output pulse from said integrating means to vary the operation of thethrottle and brake control selection means periodically in response tosaid output pulse.

4. A system according to claim 1, wherein said strain responsive meansis mounted on a drawbar which connects the helper locomotive to anadjacent car.

5. A system according to claim 1 wherein said helper locomotive hasspeed responsive means effective to detect the speed of the helperlocomotive, means connected to said speed responsive means for producinga second electrical signal proportional to the speed of the helperlocomotive, and circuit means operatively connecting said last namedmeans to said control means elfective to modify the control of saidthrottle and brake selections by said first named electrical signal.

6. A system according to claim 3 wherein said throttle and brakeselection means includes a stepping switch for selecting said throttleand brake settings, and circuit means effective to selectively operatesaid stepping switch a predetermined number of steps as governed by theamplitude of said output pulse from the integrating means and the actualposition of said stepping switch.

7. A system for controlling a helper vehicle having a plurality of speedand brake selection means for operating the helper vehicle selectivelyat distinctive speeds and degrees of braking, said helper vehicle beingcoupled in a train of cars with a control vehicle without a prime moverat a point in the train remote from a main control vehicle, comprisingmeans operatively positioned to detect the degree of force presentbetween said helper vehicle and a portion of the train of cars, meansresponsive to the degree of said detected force to produce a firstelectrical signal having characteristics in accordance with the degreeof said force, means to produce a second electrical signal correspondingto the velocity of the helper vehicle, and means responsive to both saidfirst and second electrical signals to selectively operate said speedand brake selection means to maintain said force Within predeterminedlimits.

8. A system for controlling the operation of a helper locomotive coupledin a train of cars with a main locomotive, said helper locomotive beingequipped with apparatus for selecting various throttle settings andapplying the brakes by the selective application of energy to one of aplurality of conductors, said system comprising a strain detecting meansmounted to detect forces in tension and compression exerted against thehelper locomotive when the train is in motion and operative to producean output signal the amplitude of which varies with the degree of force,said signal being of one polarity for a force in tension and of oppositepolarity for a force in compression, integrating and timing meanselectrically connected to the output of said strain detecting meanseffective to integrate said electrical signals and produce an integratedpulse at its output periodically, speed detecting means connected tosaid helper locomotive effective to produce at its output a biasingvoltage the amplitude of which is proportional to the speed of thehelper locomotive, a stepping switch having a movable contact arm and aplurality of spaced output terminals, each of said terminals beingadapted to be connected to one of said conductors whereby the movementof said arm in one direction electrically engages the terminals toadvance the throttle and in the other direction to retard the throttleand apply the brakes, and circuit selection means electrically connectedto the output of said speed detecting means and said integrating andtiming means effective to cause said stepping switch to move saidcontact arm step-by-step in opposite directions to engaged predeterminedones of said terminals in succession in accordance with the change inthe amplitude and polarity of said integrated pulses as modified by saidbiasing voltage to maintain said detected forces within predeterminedlimits.

9. A system according to claim 8 including a direction detection meansconnected operatively between strain detecting means and the integratingand timing means effective to change the polarity of said output signalwhen said helper locomotive reverse-s direction.

19. A system according to claim 8 wherein said step ping switch has afirst and second plurality of spaced terminals and a first and secondmovable contact adapted to electrically connect to each one of each saidplurality terminals in succession, an up-step means and a downstep meansoperatively connected to said movable contacts, said up-step means beingeffective to operate said movable contacts in one direction and saiddown-step means being effective to operate said movable contacts in theother direction, said circuit selection means including means connectingpreselected ones of said first plurality of terminals to preselectedones of said second plurality of terminals, unidirectional currentconducting circuit means connected across adjacent ones of eachplurality of terminals to conduct current in one selected directionacross ones of said first and second plurality of terminals, and saidcircuit selection means being effective to apply energy selectively tosaid connecting means to selectively operate said up-step and down-stepmeans through said 15 movable contacts and the terminal that it isengaging as governed by said unidirectional circuit means.

11. A system for operating a helper vehicle having speed and brakecontrol means and coupled to a train of cars remote from a controllingvehicle, said system comprising a transducer disposed for detecting andtranslating a mechanical force existing because of the coupling of thehelper vehicle to the train and caused by the efiort of the controlvehicle into an electrical signal characteristic of the degree anddirection of said mechanical force, a speed sensitive device connectedto said helper vehicle for pro viding an electrical signal proportionalto the speed of said helper vehicle, circuit means electricallyconnecting operatively the electrical signals from said transducer andfrom said speed sensitive device to said speed and brake control meansto operate selectively the speed and brake control means of said helpervehicle as governed by the characteristic of said signals to maintainsaid force within predetermined limits.

12. A system for controlling a helper locomotive coupled to a train ofcars remote from a main locomotive and having a throttle and brakecontrol selection means to operate the helper locomotive at a selectedspeed and degree of braking respectively, a transducer connected to thecoupling of said helper locomotive effective to detect and convert amechanical force in said coupling into a first electrical signal havingeither of two polarities, means operatively connected to said transducerfor integrating said first electrical signal, a tachometer generatorconnected to said helper locomotive for producing a second electricalsignal proportional to the speed of the helper locomotive, circuit meansoperatively connected to said tachometer generator for separating saidsecond electrical signal into two polarities, throttle trigger circuitmeans responsive to one of said two polarities from said integratingmeans and a like one of said two polarities from said circuit means forselectively operating said throttle control selection means, braketrigger circuit means responsive to the other of said two polaritiesfrom said integrating means and the like other of said two polaritiesfrom said circuit means for selectively operating said brake control,thereby controlling said throttle and brake of said helper locomotive inaccordance with the force in said coupling, and the speed of said helperlocomotive to maintain the force of said coupling within predeterminedlimits.

13. A control system for a helper locomotive that is connected in atrain of cars remote from -a main locomotive, said helper locomotivehaving a plurality of throttle settings, said system comprising atransducer mounted on a coupling of said helper locomotive connecting itto the train for translating tensile forces in said coupling intosignals of one polarity and compressive forces in said coupling intosignals of opposite polarity, speed responsive means connected to saidhelper locomotive effective to provide an electrical output signalproportional to the spe d of the helper locomotive, an integratoroperatively connected to said transducer effective to eliminate peakvoltages from said transducer by integrating said peaks over apredetermined time period, timing means operatively connected to saidintegrator for gating the output of said integrator at the end of saidpredetermined time period, circuit means operatively connected to saidtimer and the output of said integrator for accepting said gated signalsfrom said timer and combining said signals with said output signal fromsaid speed responsive means, and locomotive motor control meansoperatively connected to said circuit means for selectively varying saidthrottle settings as governed by said combined signals to maintain theforce in said coupling within predetermined limits.

14. A method of controlling the operation of a helper locomotive coupledto a train of cars to which a main locomotive is coupled remote fromsaid helper locomotive comprising measuring the force exerted on saidhelper locomotive by a car coupled directly to the helper locomotivewhen the train is urged in one direction by the main locomotive,measuring the velocity of the helper locomotive, and employing theactual measured velocity of the helper locomotive and the detected forceto vary the control of said helper locomotive to cause it to maintainsubstantially within predetermined limits the force exerted on saidhelper locomotive by said coupled car, therefor to cause the helperlocomotive to provide a predetermined share of the power in urging thetrain in said one direction.

15. A method of controlling the operation of a helper locomotive coupledto a train of cars to which a main locomotive is coupled remote fromsaid helper locomotive, comprising measuring the force exerted on saidhelper locomotive by a car coupled directly to said helper locomotivewhen the train is urged in one direction by the main locomotive,converting said detected force into an electric signal havingdistinctive characteristics depending upon the degree and direction ofsaid force, measuring the velocity of the helper locomotive, convertingsaid measured velocity into an electrical signal corresponding to thevelocity of the helper locomotive, and varying the control of saidhelper locomotive in accordance with the characteristices of both saidsignals to cause its power to maintain substantially withinpredetermined limits the force exerted on said helper locomotive by saidcoupled car, thereby to cause the helper locomotive to provide apredetermined eitort in urging the train in said one direction.

16. A system for controlling a helper vehicle coupled to a train of carsto which a main vehicle is coupled, said helper vehicle having aplurality of distinct throttle selections for operating the vehicle atdistinct speed, comprising means operatively positioned to detect thedegree of force existing between said helper vehicle and a portion ofthe train, means responsive to the degree of said force to produce afirst electric signal proportional in accordance with the degree of saidforce, timing means connected to the output of said force detectingmeans to cause said signal to be effective at predetermined specifiedintervals of time, means for advancing the throttle through a pluralityof settings in accordance with said throttle control selections means,and means responsive to said periodic signal effective to advance thethrottle setting by one increment only in response to each outputsignal.

17. A method of controlling the operation of a train of coupled railroadcars by a pair of locomotives, comprising coupling one of saidlocomotives between adjacent ones of said railroad cars remote from theother locomotive, measuring the force to which said one locomotive issubjected by the movement of the train as caused by the efiort of theother locomotive, converting said force into an electrical signal, thevalue of which is dependent on the amount of force and characteristic ofthe direction of force, and controlling the motor and braking power ofsaid one locomotive in accordance with the values and characteristics ofsaid electrical signal to maintain said force within predeterminedlimits.

18. A system for controlling a helper locomotive adapted to be connectedin a train of cars with a main locomotive, comprising means effective todetect the force to which the helper locomotive is subjected when thetrain is in motion, means for detecting an operating condition of thehelper locomotive, and control means responsive to both said operatingcondition detecting means of the helper locomotive and said forcedetecting means effective to select a control for the helper locomotiveto govern said helper locomotive to vary said force to provide the powerfor a predetermined portion of the train.

19. A system according to claim 13 wherein said operating conditiondetecting means generates a signal indicative of the speed of saidhelper locomotive.

2%}. A system according to claim 13 wherein said control means includesa step-by-step means operated from one step to the next step at timespaced intervals for selecting controls for governing said helperlocomotive.

References Cited by the Examiner UNITED Redyard 105-35 10 Brier 323-Hammond -61 Purifoy 105-61 Steepe -14 Cramwinkle 177-211 ARTHUR L. LAPOINT, Primary Examiner.

JAMES S. SHANK, LEO QUACKENBUSH,

MILTON BUCHLER, Examiners.

1. A SYSTEM FOR OPERATING A HELPER LOCOMOTIVE THAT IS COUPLED TO A TRAIN OF CARS TO WHICH A MAIN LOCOMOTIVE IS ALSO COUPLED, SAID SYSTEM COMPRISING MEANS FOR SELECTIVELY OPERATING THE THROTTLE AND BRAKING CONTROL OF THE HELPER LOCOMOTIVE, STRAIN RESPONSIVE MEANS MOUNTED TO DETECT THE DEGREE OF FORCE BETWEEN THE HELPER LOCOMOTIVE AND A COUPLED CAR OF THE TRAIN, ELECTRICAL MEANS OPERATIVELY CONNECTED TO SAID STRAIN RESPONSIVE MEANS TO PRODUCE AN ELECTRICAL SIGNAL PROPORTIONAL TO THE DETECTED FORCE, CONTROL MEANS RESPONSIVE TO SAID ELECTRICAL SIGNAL TO SELECTIVELY OPERATE THE THROTTLE AND BRAKING MEANS TO MAINTAIN SAID DETECTED FORCE WITHIN LIMITS SUCH THAT THE 